This invention relates generally to a liquid crystal display circuit of the matrix type and more particularly to a circuit having a transistor and capacitor associated with each picture element. Further the invention relates to a circuit for sampling a series image signal for display on a row of picture elements, for supplying said image signal to the picture element electrode, for holding of the image signal and for writing the sampled signal on the picture element electrode of the display element.
When an image signal forming a picture, for example, a television signal, is inputted as a periodically serial signal to be displayed on a matrix image display system, it is necessary to distribute and apply the inputted image signals to the picture elements in the matrix in a periodic order. In order to simplify the circuit arrangement in the vicinity of the matrix display unit it is common to provide an image signal sampling and holding circuit for each column of the matrix whereby an image signal is sampled and held for each picture element of the same row. Then the signal is transmitted to each picture element electrode by a picture element selecting transistor in the same row. An amplifier is commonly used for each column of the matrix. If a matrix has two hundred columns, two hundred amplifiers are required, and if a television picture is to be displayed in a manner similar to a cathode ray tube, at least five hundred amplifiers are required. The power consumed by the amplifiers is high and far more power is used in amplification than is required for driving the liquid crystals.
What is needed is a liquid crystal display circuit of the matrix type which uses low power and minimizes the number of components required for effective image display.